docs: def C_Reader_Harris_Gallagher_wet_venturi_tube(mg, ml, rhog, rhol, D, Do, H=1):
      r'''Calculates the coefficient of discharge of the wet gas venturi tube 
      based on the  geometry of the tube, mass flow rates of liquid and vapor
      through the tube, the density of the liquid and gas phases, and an 
      adjustable coefficient `H`.
      
      .. math::
          C = 1 - 0.0463\exp(-0.05Fr_{gas, th}) \cdot \min\left(1, 
          \sqrt{\frac{X}{0.016}}\right)
          
      .. math::
          Fr_{gas, th} = \frac{Fr_{\text{gas, densionetric }}}{\beta^{2.5}}
          
      .. math::
          \phi = \sqrt{1 + C_{Ch} X + X^2}
          
      .. math::
          C_{Ch} = \left(\frac{\rho_l}{\rho_{1,g}}\right)^n + 
          \left(\frac{\rho_{1, g}}{\rho_{l}}\right)^n
          
      .. math::
          n = \max\left[0.583 - 0.18\beta^2 - 0.578\exp\left(\frac{-0.8 
          Fr_{\text{gas, densiometric}}}{H}\right),0.392 - 0.18\beta^2 \right]
              
      .. math::
          X = \left(\frac{m_l}{m_g}\right) \sqrt{\frac{\rho_{1,g}}{\rho_l}}
          
      .. math::
          {Fr_{\text{gas, densiometric}}} = \frac{v_{gas}}{\sqrt{gD}}
          \sqrt{\frac{\rho_{1,g}}{\rho_l - \rho_{1,g}}}
          =  \frac{4m_g}{\rho_{1,g} \pi D^2 \sqrt{gD}}
          \sqrt{\frac{\rho_{1,g}}{\rho_l - \rho_{1,g}}}
          
      Parameters
      ----------
      mg : float
          Mass flow rate of gas through the venturi tube, [kg/s]
      ml : float
          Mass flow rate of liquid through the venturi tube, [kg/s]
      rhog : float
          Density of gas at `P1`, [kg/m^3]
      rhol : float
          Density of liquid at `P1`, [kg/m^3]
      D : float
          Upstream internal pipe diameter, [m]
      Do : float
          Diameter of venturi tube at flow conditions, [m]
      H : float, optional
          A surface-tension effect coefficient used to adjust for different 
          fluids, (1 for a hydrocarbon liquid, 1.35 for water, 0.79 for water in 
          steam) [-]
  
      Returns
      -------
      C : float
          Coefficient of discharge of the wet gas venturi tube flow meter
          (includes flow rate of gas ONLY), [-]
  
      Notes
      -----
      This model has more error than single phase differential pressure meters.
      The model was first published in [1]_, and became ISO 11583 later.
      
      The limits of this correlation according to [2]_ are as follows:
          
      .. math::
          0.4 \le \beta \le 0.75
          
      .. math::
          0 < X \le 0.3
          
      .. math::
          Fr_{gas, th} > 3
          
      .. math::
          \frac{\rho_g}{\rho_l} > 0.02
          
      .. math::
          D \ge 50 \text{ mm}
      
      Examples
      --------
      >>> C_Reader_Harris_Gallagher_wet_venturi_tube(mg=5.31926, ml=5.31926/2, 
      ... rhog=50.0, rhol=800., D=.1, Do=.06, H=1)
      0.9754210845876333
      
      References
      ----------
      .. [1] Reader-harris, Michael, and Tuv Nel. An Improved Model for 
         Venturi-Tube Over-Reading in Wet Gas, 2009. 
      .. [2] ISO/TR 11583:2012 Measurement of Wet Gas Flow by Means of Pressure 
         Differential Devices Inserted in Circular Cross-Section Conduits.
      '''
      V = 4*mg/(rhog*pi*D**2)
      Frg =  Froude_densimetric(V, L=D, rho1=rhol, rho2=rhog, heavy=False)
      beta = Do/D
      beta2 = beta*beta
      Fr_gas_th = Frg*beta**-2.5
      
      n = max(0.583 - 0.18*beta2 - 0.578*exp(-0.8*Frg/H), 
              0.392 - 0.18*beta2)
      
      C_Ch = (rhol/rhog)**n + (rhog/rhol)**n
      X =  ml/mg*(rhog/rhol)**0.5
      OF = (1.0 + C_Ch*X + X*X)**0.5
      
      C = 1.0 - 0.0463*exp(-0.05*Fr_gas_th)*min(1.0, (X/0.016)**0.5)
      return C